Slack tool

The Slack tool gives an agent the Slack Web API behind a single action it picks per call — 28 actions for messaging, reactions, reading and managing channels, DMs, users/profiles, files, and workspace info. One credential: a Bot User OAuth token.

Connect Slack

1. Go to api.slack.com/apps → Create New App → From scratch; name it and pick the workspace.
2. Open OAuth & Permissions → Bot Token Scopes and add the scopes for what you want the bot to do (see checklist below).
3. Install to Workspace → Allow.
4. Copy the Bot User OAuth Token (starts with xoxb-) and paste it into the tool's Bot User OAuth Token field.

Scope checklist

Add only what you need; each action the token's scopes don't cover returns a clean missing_scope error naming the scope.

• Post + react — chat:write, chat:write.public, reactions:write, reactions:read
• Read channels — channels:read, channels:history, groups:read, groups:history; self-join: channels:join
• Manage channels — channels:manage, channels:write.topic, channels:write.invites
• DMs — im:write, im:history
• Users — users:read, users:read.email, users.profile:read
• Files — files:write, files:read
• Workspace — team:read, emoji:read

Capabilities

The agent picks one action per call (28 total), grouped by area:

• Messaging — send_message (channel + text/blocks, optional thread reply), update_message (channel, ts), delete_message (channel, ts).
• Reactions — add_reaction / remove_reaction (channel, timestamp, name), get_reactions (channel, timestamp).
• Channels (read) — list_channels, get_channel, read_history, read_thread (channel, ts), join_channel.
• Channels (manage) — create_channel (name), archive_channel, rename_channel (channel, name), set_channel_topic, set_channel_purpose, invite_to_channel (channel, users).
• DMs — open_dm (users) → returns a DM channel id to send_message to.
• Users — list_users, get_user, get_user_profile, lookup_user_by_email (email).
• Files — upload_file (filename + content|file_url), list_files, get_file_info, delete_file.
• Workspace — get_team_info, list_emoji.

Field reference

• channel — a channel ID like C0123ABCD, or a DM channel ID D0123… (from list_channels / open_dm). To message a person, use their user ID or open a DM first.
• user / users — a user ID like U0123ABCD (from list_users); users is comma-separated (invite / DM).
• ts — a message's timestamp ID (e.g. 1700000000.123456) — the message to edit/delete, or a thread parent. Returned as ts when you post.
• name — for reactions, the emoji name without colons (e.g. white_check_mark); for create/rename, the channel name (lowercase, hyphens, no spaces).
• text / blocks / thread_ts — message text (Slack mrkdwn: *bold*, <url|label>, <@U123>); optional Block Kit layout; reply in a thread by passing the parent's timestamp.
• Channel management — topic / purpose (≤250 chars), is_private (create a private channel).
• Upload — filename, content (inline text) or file_url (public https to fetch), title, initial_comment.
• Paging — limit / cursor (next-page cursor from response_metadata.next_cursor), and oldest / latest / inclusive for history windows.

Common recipes

• Post an alert — send_message to #channel (the bot can post to any public channel without joining).
• Escalate in a thread — send_message with thread_ts set to the parent message.
• DM a user — open_dm → send_message to the returned DM channel id.
• Share a file/report — upload_file with content or file_url and an initial_comment.
• Read recent messages for context — read_history (the bot must be in the channel).
• Spin up a project channel — create_channel → invite_to_channel with the team's user ids.

Permissions & troubleshooting

Post anywhere, read where invited: chat:write.public lets the bot post to any public channel without joining, but reading history and reacting require the bot to be in the channel — it can join_channel first (if channels:join is granted) or be invited with /invite @YourBot. Private channels always need an explicit invite. Channels can be archived, not deleted (Slack has no delete-channel API).

Slack returns HTTP 200 even on failure; the tool detects {"ok":false} and surfaces the Slack error code (in trace/debug panels):

• not_in_channel → the bot isn't a member; join or invite it.
• missing_scope (needs scope: …) → add the scope in OAuth & Permissions, then reinstall.
• channel_not_found / users_not_found / message_not_found → wrong ID; fetch it from list_channels / list_users first.
• cant_update_message / cant_delete_message → the bot didn't author that message.
• rate_limited → Slack throttling; retry later.

Classification & lifecycle

This is a read and write tool, and it can delete messages/files and archive channels. If you run it on an autonomous bot, set its safety classification to match. It's post-call-hook eligible (runs outside the LLM turn) — e.g. post a recap or escalate to a channel after a call.